


Protective Instinct

by Bleach_ed_Na_tsu



Category: Katekyou Hitman Reborn!
Genre: Alternate Universe, Gen, Tsuna has a Twin, Twin!fic, tsuna becomes a bamf, tsuna isn't useless, twin boss
Language: English
Status: Completed
Published: 2020-03-19
Updated: 2020-03-19
Packaged: 2021-03-01 00:53:27
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,894
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23216548
Author URL: https://archiveofourown.org/users/Bleach_ed_Na_tsu/pseuds/Bleach_ed_Na_tsu
Summary: Tsuna's twin brother, Ienari, has far more potential than Tsuna (he is better than Tsuna at everything). So it's unsurprising when Reborn comes strutting in and says that it's Ienari and not Tsuna who has been chosen to be the next Vongola Boss. Tsuna isn't about to let Ienari give up his potential for a life of crime. Tsuna will steal the Vongola away from his twin.
Comments: 3
Kudos: 96





	Protective Instinct

**Author's Note:**

> I am so sorry. This is not an 'update' as such. But I really couldn't not join the band wagon, the 'twin fic' trope is so interesting. However I am tired of seeing the 'chosen twin hates/tries to kill the older twin' thing. Because I have a little more faith in Reborn and Vongola. So this is my little twist on this trope. I hope you like it.
> 
> Please review at the end since I really want to know how you think I took this idea. I think it's a little different, but there's no guarantee of that. Especially since I can't have read every single fic on this site.

You hear all sorts of stories about brothers. Sometimes they are inseparable; they play, eat, sleep, and grow together in near perfect synchronicity. Sometimes they try to slaughter each other; both literally and figuratively as they fight and beat and one-up each other.

Twins, on the other hand are a strange breed. They are a mix of the two types of brothers, constantly. There is never a separation of adoration and hate. When there is there is an imbalance enough to ruin them. Twins are special, always would be. Looking past the superstitions about feeling each-other's pain and reading each other's thoughts; twins are strange. They are born from the same place at the same time and will literally live their entire lives together. Looking at reflections of each other and their actions.

Tsuna and Ienari were no different in this aspect. They were a rarity; the first set of twins on either side of their family dating as far back as records cared to span. From the moment they were born a strange synergy thrummed through them, day in and day out. Though they couldn't feel each-other's pain nor read each-other's minds it was impossible to ignore the way they moved around each-other. They were completely aware of the presence of the other in any space. So even while the eldest was clumsy and awkward, and the youngest confident and strong, they never bumped elbows of skulls –accidentally or purposefully –they never got in each other's ways, and in fact they could be called graceful.

However, like most twins, there was a power balance. Amongst twins, one was either more charismatic or more forward than the other. After all twins for all their matched genes and upbringing, were separate people. However, it wasn't confident, proud Ienari that ruled these twins; it was Tsuna.

"Come on, little brother." Tsuna grunted as he stood, covered in dust and biting back tears.

He knew that Ienari was sitting behind the tree, waiting for him. He had watched the bullies rip into his brother, but that was the way of things. It had been the way of their lives for years now. Ienari was the popular one, he was the one people flocked to, he was the leader and Tsuna…Well Tsuna was the pariah.

Tsuna was the one that was singled out, he was the one that had no friends. He was Ienari's shield. He was the stupid one that was picked on, and therefore made Ienari seem so much more. Tsuna was the shadow that made the general populace focus on Ienari as a leader and as a friend.

It made Ienari burn with anger, but given their record, given the likelihood that both of the twins would end up at least slightly isolated, Tsuna had argued that it was better one of them be treated like crap than both of them. Tsuna has given himself up as the sacrifice for his brother.

After so many years it was difficult to change the way of life. Tsuna didn't complain, Ienari stayed behind to deal with the fallout. It was a cycle, a familiar routine.

It hurt, but there you go.

"Yeah, I'm on my way." He dipped down and picked his brother up, trying not to hiss when Tsuna whimpered under his breathe.

The pair walked in silence towards the Sawada house and it was a comfortable silence. There was nothing awkward or tense, they could read each other like they were one person. Some argued that they were one person. However, years of bullying, running and talking without words had left the twins able to figure out when a word was needed or when silence was better.

* * *

Reborn was very concerned when he rolled up into the Sawada house to find the twins stumbling in. Tsuna, the oldest, was bleeding from his mouth, holding his side as if it were throbbing. Ienari on the other hand was pulling the boy in, distracting their mother as Tsuna ran upstairs.

It was a little concerning that the boys had set up such an act, but at least they were both developing traits of the mafia.

Ienari was learning to care for his family.

Tsuna was learning to be a scape goat.

It was a little harsh perhaps. However, in the world where twins were going to inherit the throne of Vongola, they both had to be ready themselves over to the mafia. Even if one of them was going to be a sacrifice for the other.

* * *

"Good morning, Tsunayoshi, Ienari." Reborn's voice rumbled over the boys in the room. "I am your new home-tutor, Reborn."

Silence boomed in the room. Ienari and Tsuna had been sitting in their room –doing homework by the look of it. Reborn stood in the doorway, he'd already introduced himself to Nana, but had said he'd go straight up to the room when she had tried to call the boys down. A pair of brown eyes spun on Reborn, and while Ienari (he had blonder hair, it was easy for Reborn to tell them apart) was wide-eyes and curiosity, Tsuna was narrowed eyes and suspicion. It made sense, a scape-goat would need to know who was a threat and who was a friend, no use in distracting an ally when a friend could be an enemy.

"E-excuse me?" Tsuna stood then, staring down at the baby in the door. But he _was not_ a baby.

"Except, I'm not actually a school tutor. I am a hitman, and though you will improve physically and academically, I am here for something…more." Reborn just smirked, and he enjoyed the shiver of fear that rumbled through the boys. It was proof of his power, because these civilians had never felt flames press against them, and still they were scared of this tiny beast before them. "I am here to train you to be mafia men, Ienari is going to be the next boss of the Vongola Mafia. Rejoice that I am your tutor and maybe you'll survive."

Suddenly there was heat, and Reborn could only blink. The boys weren't supposed to have flames yet. The Ninth and Iemitsu had sealed off the twins' sky flames long before now. The boys had been only six when they were sealed away, they shouldn't have any heat to them. Yet here it was, that sweet scent of flames-almost-released.

Surprisingly, it was not Ienari with swirling eyes, but Tsuna. The boy had Ienari pushed almost completely behind him, Ienari was almost crying, not really understanding what Reborn was saying. Tsuna though, he seemed to comprehend. "You've got to be joking." And it wasn't a question, Tsuna was serious, a snarl in place of what would have been a stutter, perhaps.

Reborn let Leon fall into his hand, and as she glowed and changed, Reborn could see shock fill Ienari's entire body, and fury fill Tsuna's. Fury and resignation in equal parts. "Oh, but I'm not. I am the greatest hitman in the world. Ienari will be boss by the time I'm done. You will stop being a disgrace, and will be able to defend yourself."

Tsuna stepped forward then, but he didn't leave his twin behind. He pulled Ienari with him; leaving no space for Reborn to somehow get between them. When Ienari gripped his shirt, Tsuna's protective instinct flared violently. "Oi, do you think I'm going to let you take Ienari away. He can't be a Mafia boss."

But Tsuna didn't deny that this was true. Their father was a strange one, and Tsuna could tell that something was odd about the way the man looked at Tsuna and his brother when he came home. Testing them as a pair and individuals. Tsuna remembered a time when they had flames in their hands as children, and then suddenly when they did not.

"You don't need to be concerned." Reborn's voice was cold as he regarded the older twin. Tsuna hadn't been chosen to be boss, he was only a little of Reborn's concern. "Though we will have to improve those abysmal grades of yours, you don't need to get involved."

And with that, Reborn strutted out of the room. Oh he felt the fire on his spike as Tsuna's eyes bore into his own. However, with his back turned, Reborn didn't notice the fire and orange glaze on the older twin's eyes.

Tsuna grew angrier as he stood there, watching as Reborn trod down the stairs, the man had disregarded him, and while that was normal, in this instance there was nothing Tsuna loathed more.

"N-Nii-san." Tsuna was broken from his reprise when he heard the choked voice behind him.

The oldest twin turned on his heel, and had Ienari been less scared he may have gasped in wonder. Tsuna was no longer pathetically wide-eyed. Instead, his big brother finally looked like Ienari knew he could; he looked brave, protective even. He looked strong in his own way. His eyes were swirled with orange, and his mouth set in a firm line. But Ienari _was_ terrified, and tears burned in his eyes. He could feel his mouth dry instantly, and his heart thumping in his chest started to unnerve his breathing.

"Nii-san, w-what are we….I can't, I'm scare-."

"Don't worry." And Tsuna stepped forward. He took Ienari's face in his hands, his eyes growing more orange as he spoke. "We'll figure it out."

"Please." Ienari was desperate, he was breathing hard, his eyes were tearing over, and he knew he shouldn't be but he was terrified. He shouldn't be worried, because his Nii-san had promised everything would be alright, and his Nii-san was never wrong. "Please, I can't do this, Nii-san. I can't. I'm not boss material; I can't do the Mafia thing. Please, Nii-san, what can we do. I can't be a boss, I can't. I'm going to be normal, live with a good job and a wife and-."

Tsuna smiled sadly and it cut Ienari off. He hadn't seen that look for a long time. The last time his brother had looked so self-sacrificing was before Ienari was popular and loved. It was when they were only babies. It surprised Ienari that he still remembered the look, then again it was such a startling, and scarring look.

After all, it was the first time Tsuna had allowed himself to be beat while his little brother escaped.

"I will be the Boss, Ienari. I won't let your potential go to waste. I mean, Reborn seems pretty serious."

"But you can't, you have-."

"A life?" Tsuna cut off with a sardonic bark of laughter. "I do not have a future, Ienari; but you do. I won't let that go to waste. I _**will**_ protect your future, Ienari." Tsuna's eyes were almost wholly golden by now, and Ienari was captivated. He also found himself believing his big brother so completely that he suddenly could breathe. But then Tsuna was shoving him towards the still open door. "Now go make sure Mama is alright, I will be down in a moment."

Ienari looked back only once over his shoulder before he went downstairs. Tsuna stood in the bedroom, light cast on him from the dropping sun, and while Ienari would swear (until training actually began) that he was just high on adrenaline, in that moment, Ienari could only think that Tsuna looked as if he were surrounded by golden flames. Instead, Ienari blinked and went downstairs.

"Mama! That crazy baby hasn't hurt you has he?!"

"What? Don't be silly Ienari, Reborn-chan has been an angel."

Once out of sight, Tsuna let out a huffed breath and his knees gave you. He barely managed to get a hand on his chair before he hit the ground. A sudden heat built up through his body, bringing sweat to his brow and chest and down his back. His eyes were no longer orange, and he felt as if he had a hundred and fifty pounds resting on his chest.

"Come-on Tsuna, you can do it. Don't get scared now." Tsuna muttered to himself as he looked at the stairs, willing himself to breathe and move. "You've promised you little brother you'll protect him.

And that's what Tsuna would do.

As the young boy made his way down the stairs, pale and panting slightly from the exertion –which he thought was from fear –he was unaware of the stares following his every move. Contrary to popular belief, Reborn was a fair man. The Ninth's orders had been to train both boys to the same standard; but he had been ashamed of both his Boss' and Iemitsu's bias towards Ienari. It wasn't fair or right to be bias until training began, every person had different potential, and certain situation brought the best out of the unsuspecting. Reborn had come into the home hoping to find out how true their bias was.

Turns out very true. Ienari was a great student. He was true and enjoyed learning. He genuinely cared about his teammates in various sports, and his studies, and he also cared for his brother. He would make a good boss. However, Reborn had wanted to know more. He _needed_ to know more. Especially about Tsunayoshi.

And boy had Reborn not been disappointed. The boy had potential. But that was it. He was unskilled, unconfident when confronted, and lacked all skill in academics or athletics. However, the potential pouring from his entire being when his family was in danger set even Reborn's teeth on edge.

After all, the boy had very nearly ignited Dying Will in a non-life-threatening situation. Only aged and matured bosses could do that; only the most skilled and practiced. For a child, and certainly some boy who had yet to reach sixteen, to pull that off, simply with a threat to _theirs_ ….well it was unfounded and warranted more investigation.

Reborn had come to train both boys, but he had promised to go into the Sawada residence with the bias of making Ienari Vongola Decimo, and ensuring that Tsuna had the skills to at least keep himself alive –but not thriving –in the civilian world he would be living in –regardless of the fact that it would be constantly tainted by mafia influence one way or another.

Now that he had a good look at the boys though, Reborn was more than intrigued. Reborn would train them both. He would train them well. Already, however, Reborn could almost foresee which boy would be boss. There was only one kind of Boss that Reborn agreed with after all, and it wasn't always the most academic, or athletic person either.

* * *

That evening, Reborn laid in the hammock strung from the corner of the boys' room. He was as quiet as he could possibly be, feinting sleep so as to let the boys calm. They had been jumpy all day as Reborn had watched them.

He didn't blame them, both seemed to have an innate sense –perhaps Vongola intuition rearing up now that a true threat had emerged –that Reborn was not a child, and should not be seen nor treated as such.

Ienari, once he had seen Tsuna relax had dropped off almost immediately. Tsuna on the other hand, had looked over at Ienari and sighed. It seemed the boy was all and everything for his family.

"Reborn," the young brunet asked with mild hesitation, "can you be straight with me?"

"I can try, I am your tutor and there is no sense lying to a student." Reborn replied gruffly. He had hoped the boys thought him asleep.

Tsuna seemed to sigh in relief before rolling over and looking towards Reborn's place in the room. "Do you truly intend to train us equally? Do I stand a chance against your Boss' and my father's preference?"

The Hitman hummed slightly, trying to think how to phrase this next answer. He could lie here and tell the boy he was never going to be boss, to test his resolve; or he could be truthful and tell him how difficult it was going to be for the boy. There was no sense, in Reborn's eyes, to lie in a way that would give the boy false hope.

Especially not when his body and mind were fighting each other; his eyes were orange again, and Reborn could almost smell the strain it was putting on the boy.

Reborn may have to get Shamal in earlier than he thought if this child's flame was going to try and force itself out before his body was ready.

"It is going to be difficult for you. Your father and the Ninth are insistent that you be left as well alone as you can be. They do not think you are fit to be boss in any respect."

Reborn couldn't tell if the boy was put out by that statement or outraged, Reborn could feel the faintest buck in a flame core; and considering Tsuna's was apparently inactive, that was saying something.

"But I promise you, I will train you both and will chose the truly worthy boss."

Tsuna stared, his eyes glowing in the dark. "I will work hard."

Reborn, for all his tricks and traps, did not doubt the boy's resolve one bit. Nor did he doubt the potential of this Dame-Tsuna.

"I look forward to it."

**Author's Note:**

> So there you go. A little chapter of the start of this fic. It may seem a little mismatched and rushed, but I don't envision this being an extraordinarily long series. I have planned out a few chapters, but mostly it's going to be written on a whim.
> 
> Please review!
> 
> ~~Bleach-ed-Na-tsu :3


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